RELATIVISTIC BAND STRUCTURE OF GeTe, SnTe, PbTe, PbSe, AND PbS

Abstract

R6sum6.-Les calculs relativistes de bandes par la methode des ondes planes orthogonaliskes ont ktk menks A bien aux points de symetrie simple dans la zone rkduite de Brillouin pour plusieurs composCs IV-VI. La structure de bande dans le reste de la zone a et6 deduite par interpolation. A notre connaissance, ce sont les premiers calculs de bandes pour Ies composb IV-V1 qui se basent au depart sur des principes relativistes (contrairement aux calculs non relativistes affines par des corrections relativistes et de couplage spin-orbite). Nos calculs conduisent A des modkles de bandes ayant une rkalitk physique, qui sont suffisamment prkcis pour tenir compte de la plupart des singularitks des spectres expkrimentaux de rkflectivitk. 11 est difficile #interpreter les spectres d'kectroreflectivite sans ambigufte a l'aide de ces modeles de bande mais un certain nombre de recoupements plausibles dans les spectres peuvent &re faits. Des calculs des bandes d'energie et de spectre optique plus Claborks se poursuivent et seront publies ailleurs. Abstract.-Relativistic OPW band calculations have been carried out at key points in the reduced zone for several IV-V1 compounds. The band structure in the remainder of the zone has been filled in with the aid of an interpolation scheme. To our knowledge, these are the first fully relativistic first-principles band calculations for IV-V1 compounds (in contrast to non-relativistic calculations supplemented by relativistic and spin-orbit coupling corrections). Our first-principles band calculations lead to physically realistic energy band models which are sufficiently accurate to account for most of the characteristic features of the experimental reflectivity spectra. It is difficult to interpret the electroreflectivity spectra unambiguously in terms of these band models but a number of plausible spectral assignments can be made. Refined energy band and optical spectrum calculations are in progress and will be reported elsewhere.

Convergence of electronic bands for high performance bulk thermoelectrics

“…Similar conclusions can be made on the sample with x=0.15 because of its close values of b and f L with x=0 even though its higher carrier density. The smaller deformation potential for the heavy hole (Σ) band as compared with that of light hole (L) band, is presumably due to the different location in k-space 3, 11,12,29 , which is similar to other semiconductors such as Si and Ge 30 .…”

Photoelectric Properties of the Lead Chalcogenides

“…Tung and Cohen [6] binding energy(eV1 - These three peaks are labelled I, 11, and 111, in order of decreasing electron energies. These peaks are, as usual, superimposed on a background due to secondary electrons which increases with debreasing electron energy.…”

Optimization of thermoelectric efficiency in SnTe: the case for the light band

“…[1][2][3] One mechanism of p-type PbTe's outstanding thermoelectric performance is thought to be due to its complex valence band structure, especially at high temperatures where the energy of primary and secondary maximums are thought to be aligned-leading to extraordinarily high valley degeneracy. 4 In SnTe, one might also expect good thermoelectric performance because it shares many of the same characteristics with PbTe; specifically, both exist in the rock salt crystal structure and both have multiple valence bands 5 which contribute to the thermoelectric properties. However, unlike PbTe, SnTe is inherently riddled with defects which results in a heavily doped ( p B 10 20 -10 21 cm À3 ) material and a mediocre zT (around 0.5 at 900 K).…”